1. Field of the Invention
The invention relates to photo-endoscope having an electronic flash-tube and more particularly to a photoendoscopes having an electronic flash-tube inserted in a metal telescope tube on the distal side of the viewing port, the flash-tube being provided with an enveloping transparent protective sheath and together with a transparent cast substance being arranged in a metal housing provided with an aperture lying in the viewing direction, a fibre light-conductor of crescent-shaped cross-section being positioned around the telescope tube between two mutually eccentric tubes and terminating with its maximum thickness on the proximal side of the viewing port of the telescope. Such a photoendoscope may be referred to as an endoscope of the kind described.
2. Description of the Prior Art
It is known to arrange an electronic flash-tube at the proximal end of a photoendoscope and to conduct not only the normal light for observation but also an electronic flash to produce photos into a body cavity by means of a light-conducting cable. This proximal photographic illumination by means of the flash-tube presents no danger to the doctor or patient but does involve considerable expense.
When endoscope telescopes of large diameter can be used, it has been the practice because of the lower cost, to mount the electronic flash-tube in the distal end of the telescope, which gives a picture of better quality and, because of the wide angle of illumination, optimum lighting of the object and the surroundings. A disadvantage however is the risk of the electronic flash-tube fracturing as a result of the fact that, although the tubes are of small dimensions, large amounts of electrical energy are released when the flash is triggered. With aim of preventing splinters from penetrating the body cavity should the flash-tube explode or burst, flash tubes arranged in a holder formed by a housing have already been enclosed in transparent protective sleeves and the space between the flash tube and the protective sleeve filled with a transparent, usually cast, heat-resistant substances. This however does not provide complete protection since under certain circumstances the protective sheath itself may burst or splits may develop in the sheath with the result that splinters from the flash-tube or the transparent cast substance enclosing the flash-tube can find their way into the body cavity, which may be harmful to the patient and create considerable problems for the doctor.
The main object of the invention is therefore to provide satisfactory protection against splinters or the like penetrating into the body cavity in the event of the electronic flash-tube bursting, as it may under certain circumstances.